Background Focal prefrontal cortex repetitive transcranial magnetic stimulation (rTMS) was originally investigated as a potential antidepressant under the assumption that in depressed patients, prefrontal cortex stimulation would produce changes in connected limbic regions involved in mood regulation. Methods Fourteen adult patients with depression were scanned in a 1.5-T scanner using interleaved rTMS (1 Hz) applied on the left prefrontal cortex over 7.35 min. Images were analyzed with Statistical Parametric Mapping 2b and principal component analysis. Results Over the left prefrontal cortex, 1-Hz TMS was associated with increased activity at the site of stimulation as well as in connected limbic regions: bilateral middle prefrontal cortex, right orbital frontal cortex, left hippocampus, mediodorsal nucleus of the thalamus, bilateral putamen, pulvinar, and insula (t = 3.85, p < .001). Significant deactivation was found in the right ventromedial frontal cortex. Conclusions In depressed patients, 1-Hz TMS at 100% motor threshold over the left prefrontal cortex induces activation underneath the coil, activates frontal-subcortical neuronal circuits, and decreases activity in the right ventromedial cortex. Further work is needed to understand whether these immediate changes vary as a function of TMS use parameters (intensity, frequency, location) and whether they relate to neurobiologic effects and antidepressant mechanisms of TMS.
Bibliographical noteFunding Information:
This work was supported in part by grants from the National Alliance for Research in Schizophrenia and Depression (Independent Investigator Award to MSG), the Borderline Personality Disorder Research Foundation, National Institute of Mental Health Grant No. R01 RR 14080-02 (DEB), the Stanley Foundation (MSG), National Institute on Alcohol Abuse and Alcoholism Grant No. 2 P50 AA10761-03 (MSG), National Institute of Mental Health Grant No. R01 RR14080-01 (MSG), National Institute of Neurological Disorders and Stroke Grant No. R01 NS40956-1 (MSG), and the Defense Advanced Research Projects Agency Grant No. DARPA-10536 (MSG). The Brain Stimulation Laboratory has also received grant support from Cyberonics (vagus nerve stimulation) and Neotonus (transcranial magnetic stimulation) for clinical trials. This study was presented in abstract form at the annual meeting of Society of Biological Psychiatry, May 17, 2003, in San Francisco.
- Brain networks
- Limbic system
- Prefrontal cortex
- Transcranial magnetic stimulation